Emacs Evil mode: how to create a new text object t

问题:

I am trying to create a new text object in Evil. For example, the text object iw will only select subsets of strings containing hyphens. I want the new text object to match words with any non-space characters. What I got so far is:

(evil-define-text-object evil-inner-space (count &optional beg end type)
  "Select inner space."
  :extend-selection nil
  (evil-regexp-range count beg end type "[ \n]" " " t))

(define-key evil-inner-text-objects-map " " 'evil-inner-space)

This code fails to correctly match words at the end of a line. It works for words at the beginning of a line thanks to \n.

I tried many things that did not work. The trouble for me is that when something does not work, I don't know if it is due to a wrong regexp or to limitations in evil-regexp-range. For example, using \s- reports an error, which seems to be a limitation in Evil.

回答1:

Update: evil-regexp-range was recently replaced with evil-select-paren. This works on current evil and has the same usage as the old one:

(defmacro define-and-bind-text-object (key start-regex end-regex)
  (let ((inner-name (make-symbol "inner-name"))
        (outer-name (make-symbol "outer-name")))
    `(progn
       (evil-define-text-object ,inner-name (count &optional beg end type)
         (evil-select-paren ,start-regex ,end-regex beg end type count nil))
       (evil-define-text-object ,outer-name (count &optional beg end type)
         (evil-select-paren ,start-regex ,end-regex beg end type count t))
       (define-key evil-inner-text-objects-map ,key (quote ,inner-name))
       (define-key evil-outer-text-objects-map ,key (quote ,outer-name)))))

---

Original Answer:

If you end up defining more than one new text object, the repetition can get annoying, especially if you want to bind both inner and outer objects. If you hit that barrier, try this:

(defmacro define-and-bind-text-object (key start-regex end-regex)
  (let ((inner-name (make-symbol "inner-name"))
        (outer-name (make-symbol "outer-name")))
    `(progn
      (evil-define-text-object ,inner-name (count &optional beg end type)
        (evil-regexp-range count beg end type ,start-regex ,end-regex t))
      (evil-define-text-object ,outer-name (count &optional beg end type)
        (evil-regexp-range count beg end type ,start-regex ,end-regex nil))
      (define-key evil-inner-text-objects-map ,key (quote ,inner-name))
      (define-key evil-outer-text-objects-map ,key (quote ,outer-name)))))

Usage:

; between dollar signs:
(define-and-bind-text-object "$" "\\$" "\\$")

; between pipe characters:
(define-and-bind-text-object "|" "|" "|")

; from regex "b" up to regex "c", bound to k (invoke with "vik" or "vak"):
(define-and-bind-text-object "k" "b" "c")

(This is more than you wanted, but I'll leave it here in case it helps someone :)

回答2:

I don't think you need to create a new text object. Evil includes the symbol text object. The symbol syntax is defined by the major-mode and usually includes hyphens, numbers, underscores and other non-whitespace characters.

The symbol text object is bound to o. The definition is at evil-maps.el at Bitbucket

回答3:

The correct regexp is " \|.?$". The following code implements a new text object matching any nonspace character.

(evil-define-text-object evil-inner-space (count &optional beg end type)
  "Select inner space."
  :extend-selection nil
  (evil-regexp-range count beg end type "[ \n]" " \\|.?$" t))